The silver halide color photographic materials usually comprises a support, a blue sensitive layer, a green sensitive layer and a red sensitive layer. In the image formation, the photographic material is imagewise exposed to light with respect to a multicolor object, and the silver halide is color-developed to form a color image of cyan, magenta, yellow or other colors.
A DIR (development inhibitor releasing) coupler has been known as an additive of a color negative film. A development inhibitor is released from the coupler in the color development process of a color photographic material. Using the DIR coupler, the sharpness of the image is improved by an edge effect, which is caused by the difference in the density of the released development inhibitor. The DIR coupler is effective in a color developing process of a color negative film or a color paper. However, the effect of the DIR coupler cannot be expected in other color photographic materials such as a color reversal film, a color reversal paper, and a black and white photographic material, since the main process in the image formation of these photographic materials is a black and white development.
A DIR-hydroquinone which releases a development inhibitor in the black and white development process has been known (cf., U.S. Pat. Nos. 3,364,022 and U.S. Pat. No. 3,379,529, and Japanese Patent Provisional Publications No. 50(1975)-62435, No. 50(1975)-133833, No. 51(1976)-51941, No. 50(1975)-119631, No. 52(1977)-57828, No. 62(1987)-103639 and No. 62(1987)-251746). The edge effect in the black and white development process can be obtained by the DIR-hydroquinone.
Further, Japanese Patent Provisional Publication No. 64(1989)-546 describes an image forming method improved in sharpness and graininess of the image. This method contains a black and white development process, and uses a silver halide photographic material containing a DIR-hydroquinone in a hydrophilic colloidal layer not containing silver halide.
However, these known DIR-hydroquinones are insufficient for increasing the sharpness of the image.